<p>Converts block references, polylines, splines, ellipses, texts, dimensions and hatches
into more basic entities. Dimensions are split up into lines, triangles and
text entities. Text entities are split into lines, arcs and splines if
appropriate. Splines are converted into polylines with line segments. Ellipses
are converted into polylines with arc segments.
Polylines are split up into loose segments.</p>
